1. Field of the Invention
The present invention relates to a magnetophoresis type display device which makes use of a magnetic field to make magnetic particles sealed in the display device magnetically float and display an object and to a process of production of the same.
2. Description of the Related Art
Known in the art for example are the magnetophoresis type monochrome display devices disclosed in Japanese Examined Patent Publication (Kokoku) No. 59-47676, Japanese Examined Patent Publication (Kokoku) No. 57-46439, and Japanese Utility Model Registration No. 1428562. In these magnetophoresis type monochrome display devices, the sealed space between the display panel sheet and the back panel sheet is divided into a large number of cells in which are sealed liquid dispersions containing black magnetic particles and a white fluid. By moving a recording magnetic member etc. (for example a xe2x80x9cmagnetic penxe2x80x9d) in contact with the outer surface of the front panel sheet, the black magnetic particles in the dispersion sealed in the cells corresponding to the path traced by that member magnetically float from the bottom to the front panel sheet side by the magnetic action of the member. As a result, some sort of monochrome display is formed by the difference in contrast between the white fluid and the black magnetic particles at the outer surface of the transparent front panel sheet.
Further, Japanese Examined Patent Publication (Kokoku) No. 8-7532 discloses the various conditions for the black magnetic particles in the liquid dispersion sealed in a magnetophoresis type monochrome display device for obtaining a good monochrome image display at the outer surface of the front panel sheet. Further, Japanese Unexamined Patent Publication (Kokai) No. 8-183291 discloses that the content of the black magnetic particles in the liquid dispersion sealed in the magnetophoresis type display device should be 15 to 20 parts by weight with respect to 100 parts by weight of the dispersion medium.
Further, recently, as shown in Japanese Unexamined Patent Publication (Kokai) No. 11-149265, Japanese Utility Model Registration No. 3048929, and Japanese Utility Model Registration No. 3047170, magnetophoresis type color display devices able to display multiple colors have also been proposed.
In such magnetophoresis type display devices of the related art, it has been sought to eliminate the image breaks in display at the boundary portions of the individual cells and improve the black and white contrast or the color contrast.
In particular, in magnetophoresis type color display devices, a display device which is free from color bleeding, has clear hues, and can improve the resolution of the color display image has been sought.
In order to obtain a good image display at the outer surface of a front panel sheet, in particular to eliminate the image breaks in display at the boundary portions of the individual cells and improve the contrast of the display image and the resolution of the display image, however, it was made clear by experiments of the present inventors that it is not enough to specify certain conditions of the magnetic particles and, further, it is not enough to just define a certain content of the magnetic particles in the liquid dispersion.
Further, in the magnetophoresis type display devices of the related art, there was the problem of disposal since the front panel sheets were made of polyvinyl chloride. Further, in the process of production of magnetophoresis type display devices of the related art, the work of precisely filling the liquid dispersion containing the magnetic particles in the individual cells was difficult. The individual cells were liable to be either filled too much or too little with the liquid dispersion. Due to this, problems were liable to occur such as image breaks in the display at boundary portions of the individual cells or a reduction in the black and white contrast or color contrast.
The present invention was made in view of this situation and has as its first object to provide a magnetophoresis type display device which can display an excellent image at the front panel sheet, in particular can eliminate the image breaks in display at the boundary portions of the individual cells and can improve the contrast of the display image and the resolution of the display image.
Further, the present invention has as its second object to provide a magnetophoresis type color display device which can display a color image, in particular can eliminate the image breaks in display at the boundary portions of the individual cells, eliminate color bleeding, give clear hues, and improve the resolution of the color display image.
Further, the present invention has as its third object to provide a magnetophoresis type display device which is environmentally friendly at the time of disposal and further which can eliminate the image breaks in display at the boundary portions of the individual cells and can improve the contrast and a process for production of the same.
Still further, the present invention has as its fourth object to provide a process for production of a magnetophoresis type display device which facilitates the precise filling of a liquid dispersion containing magnetic particles in the individual cells and thereby enables the liquid dispersion to be filled in the individual cells without excess or shortage.
The present inventors engaged in intensive studies to achieve the first object and as a result discovered that by defining the effective magnetic flux densities at the panel surface due to the recording magnetic member and the erasing magnetic member and maintaining an overall predetermined relationship among the various conditions of the magnetic particles, the ratio of content of the magnetic particles in the liquid dispersion, etc. it was first possible to eliminate the image breaks in display at the boundary portions of the individual cells and improve the contrast of the display image and the resolution of the display image and thereby completed a first aspect of the present invention.
That is, according to the first aspect of the present invention, there is provided a magnetophoresis type display device (including magnetophoresis type color display device, same below) comprising:
a transparent front panel sheet,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space into a large number of cells,
a liquid dispersion containing magnetic particles to be sealed inside the cells formed by partitioning by the partitioning member,
a recording magnetic member provided to be able to move along the outer surface of the front panel sheet and having a magnetic force of an extent giving an effective magnetic flux density of 100 to 500 Gauss at the outer surface of the back panel sheet in the state when the recording magnetic member is brought into contact with the outer surface of the front panel sheet, and
an erasing magnetic member arranged at the outer surface of the back panel sheet and having a magnetic force of an extent giving an effective magnetic flux density of 100 to 1500 Gauss at the outer surface of the front panel sheet in the state when the erasing magnetic member is brought into contact with the outer surface of the back panel sheet.
When the magnetic force of the recording magnetic member and/or the erasing magnetic member is too small, the magnetophoresis action in the cells is weak, so the display/erasure at the display device tends to become difficult. Further, when the magnetic force is too large, the magnetic field is too strong, so even magnetic particles which should originally not be made to magnetically float end up magnetically floating and detract from the resolution of the displayed object at the screen.
Further, to achieve the first object, according to a second aspect of the present invention, there is provided a magnetophoresis type display device comprising:
a transparent front panel sheet,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space into a large number of cells, and
a liquid dispersion containing magnetic particles to be sealed inside the cells formed by partitioning by the partitioning member,
the magnetic particles having a magnetization of at least 20.0 emu/g when a magnetic field of 500 Oe is applied to the magnetic particles, more preferably at least 22.0 emu/g and
the liquid dispersion containing 80 to 90 wt % of a single-color fluid and 10 to 20 wt % of magnetic particles.
In the present invention, if the ratio of content of the magnetic particles in the liquid dispersion is too low, the amount of the magnetic particles will be too small, so the resolution of the displayed object at the screen of the display device will end up deteriorating. For example, lines or letters will become thinner and may be broken in the middle. Further, if the ratio of content of the magnetic particles is too high, the density of the displayed object at the screen of the display device can be made high, but the single-color fluid will easily be contaminated and therefore the single color (for example, white) of the panel will become weaker at the time of erasure and the contrast will be reduced.
The magnetic particles have a magnetization of at least 20.0 emu/g when a magnetic field of 500 Oe is applied to the magnetic particles, more preferably at least 22.0 emu/g and, further, have a magnetization of at least 8.0 emu/g when a magnetic field of 200 Oe is applied to the magnetic particles, more preferably at least 10.0 emu/g. The magnetic particles must have a magnetization enabling magnetophoresis by the action of the low magnetic field of the recording magnetic member or the erasing magnetic member. By giving them this range of magnetization, the magnetic particles sufficiently magnetically float and the display and/or erasure at the screen of the display device is improved.
The viscosity of the single-color fluid is preferably 200 to 800 cp at 25xc2x0 C., more preferably 300 to 600 cp. If the viscosity of the single-color fluid (white fluid) is too low, the single color (whiteness) of the single-color fluid (white fluid) will become weak and will tend not to be able to completely conceal the color of the colored magnetic particles from the screen when erasing an image (displaying the single color at the screen). If the viscosity of the single-color fluid (white fluid) is too high, the single color (whiteness) of the single-color fluid (white fluid) will end up concealing the hue of the magnetic particles resulting in the inability to obtain a clear hue display and further preventing smooth magnetophoresis of the magnetic particles and necessitating an increase in the magnetic flux density of the recording magnetic member or erasing magnetic member.
As the single-color fluid, one of a color having a high contrast with respect to the color of the magnetic particles is preferred. While not particularly limited, a white fluid is preferred. Further, as the coloring agent contained in the magnetic particles, a black coloring agent is preferred. As the black coloring agent, carbon is preferably used.
The white fluid may be one including at least titanium oxide and silicon oxide in which when the total weight of the white fluid is 100 wt %, the wt % of the titanium oxide in the white fluid is C, and the wt % of the silicon oxide is D, the weight ratio C/D is preferably in the relationship of 1xe2x89xa6C/Dxe2x89xa62.5, more preferably 1.2xe2x89xa6C/Dxe2x89xa62.0.
If C/D is too small, the viscosity of the white fluid (single-color fluid) becomes highxe2x80x94preventing smooth magnetophoresis of the magnetic particles and necessitating an increase in the magnetic flux density of the recording magnetic member or erasing magnetic member. Further, the resolution of the displayed object displayed at the screen of the display device tends to end up deteriorating.
If C/D is too large, when the display device is left standing, the white fluid (single-color fluid) will tend to end up separating into a dispersion medium (paraffin etc.) layer and oxide (titanium oxide, silicon oxide, etc.) layer in a short time, which will make it impossible to display the color of the magnetic particles clearly at the screen. For example, when a recording magnetic member such as a magnetic stamp is brought into contact with the screen to make something be displayed on the screen, the white particles (single-color particles) comprised of the oxides will end up floating up in the direction of the screen together with the magnetic particles and will prevent the color of the magnetic particles from being reproduced clearly at the screen.
The white fluid may also be one including at least titanium oxide and silicon oxide in which when the total weight of the white fluid is 100 wt %, the wt % of the titanium oxide in the white fluid is C, and the wt % of the silicon oxide is D, the weight C+D is preferably in the relationship of 3.0 wt %xe2x89xa6C+Dxe2x89xa66.0 wt %, more preferably 3.5 wt %xe2x89xa6C+Dxe2x89xa65.5 wt %. If the ratio of content of C+D is too small, the whiteness (single color chromaticity) in the white fluid will be low and the white (single color) at the screen will be inferior, so the screen of the display device will tend to appear dirty. Further, if the ratio of content of C+D is too large, the viscosity of the white fluid (single-color fluid) becomes highxe2x80x94preventing smooth magnetophoresis of the magnetic particles and necessitating an increase in the magnetic flux density of the recording magnetic member or erasing magnetic member. Further, the resolution of the displayed object displayed at the screen of the display device tends to end up deteriorating.
The white fluid may be one including at least isoparaffin and a mixture of a plurality of white inorganic oxides in which when the total weight of the white fluid is 100 wt %, the wt % of the isoparaffin in the white fluid is A and the wt % of the mixture of the white inorganic oxides is B, the weight ratio A/B is preferably in the relationship of 10xe2x89xa6A/Bxe2x89xa620.
The single-color fluid may be one including at least a dispersion medium (not limited to isoparaffin and including other dispersion media) and a single-color pigment (not limited to white inorganic oxides and including other pigments, dyes, coloring agents, etc. and also not limited to white) in which when the total weight of the single-color fluid is 100 wt %, the wt % of the dispersion medium in the single-color fluid is Axe2x80x2, and the wt % of the single-color pigment is Bxe2x80x2, the weight ratio Axe2x80x2/Bxe2x80x2 is preferably in the relationship of 10xe2x89xa6Axe2x80x2/Bxe2x80x2 less than 20.
If the weight ratio A/B (Axe2x80x2/Bxe2x80x2) is too large, the whiteness (single color) of the white fluid (single-color fluid) will become weak and will tend not to be able to completely erase the color of the magnetic particles when erasing a display image and the panel screen will appear dirty. Further, if A/B (Axe2x80x2/Bxe2x80x2) is too small, the whiteness (single color) of the white fluid (single-color fluid) will end up concealing the hue of the magnetic particles resulting in the inability to obtain a clear hue display.
The magnetophoresis type display device according to the second aspect of the present invention may further comprise a recording magnetic member able to move along the outer surface of the front panel sheet, the recording magnetic member preferably having a magnetic force of an extent giving an effective magnetic flux density of 100 to 300 Gauss at the outer surface of the back panel sheet in the state when the recording magnetic member is brought into contact with the outer surface of the front panel sheet. The specific shape of the recording magnetic member is not particularly limited and may include a magnetic pen or a magnetic stamp or various forms.
Further, the magnetophoresis type display device according to the second aspect of the present invention may further comprise an erasing magnetic member arranged at the outer surface of the back panel sheet, the erasing magnetic member having a magnetic force of an extent giving an effective magnetic flux density of 100 to 300 Gauss at the outer surface of the front panel sheet in the state when the erasing magnetic member is brought into contact with the outer surface of the back panel sheet. The erasing magnetic member is preferably arranged to be able to move along the outer surface of the back panel sheet.
The thickness of the sealed space is preferably 0.8 to 1.5 mm, more preferably 1.00 to 1.40 mm. If the thickness is too small, it is necessary to adjust the single-color chromaticity (for example, white chromaticity) of the single-color fluid for concealing the hue of the magnetic particles in the cells by including a larger amount of the single-color particles (for example, white particles) in the single-color fluid. As a result, the viscosity of the single-color fluid becomes highxe2x80x94preventing smooth magnetophoresis of the magnetic particles and necessitating an increase in the magnetic flux density of the recording magnetic member or erasing magnetic member. Further, the resolution of the displayed object displayed at the screen of the display device tends to end up deteriorating.
Further, if the thickness of the sealed space is too large, in order to make the magnetic particles sufficiently magnetically float to the front panel sheet side in the cells, since the magnetophoresis distance is long, it is necessary to increase the magnetic flux density of the recording magnetic member or the erasing magnetic member. Further, the magnets attached to the recording or erasing magnetic member end up becoming higher in cost. Further, the resolution of the displayed object displayed at the screen of the display device tends to end up deteriorating.
The magnetic particles preferably contain 60 to 90 wt %, more preferably 70 to 85 wt % of a magnetic material and 10 to 40 wt %, more preferably 15 to 30 wt % of a synthetic resin and/or coloring agent. By using these magnetic particles, the image breaks in the display at the boundary portions of the cells are eliminated and the display quality is improved.
Further, the mean particle size of the magnetic particles is preferably 50 to 200 xcexcm, more preferably 75 to 150 xcexcm. By using magnetic particles of such a particle size, the resolution at the screen of the display device is improved, the cause of contamination of the single-color fluid is eliminated, and the display quality is improved.
The front panel sheet is preferably comprised of polyethylene terephthalate.
The partitioning member is not particularly limited, but preferably is a honeycomb structure having a large number of substantially regular hexagonal tubular cells. The honeycomb structure preferably is comprised of paper coated with a resin. Further, it may be comprised of microcapsules in which a liquid dispersion is sealed.
The partitioning member is preferably a resin-coated paper because compared with a synthetic resin, paper is a natural material, can be formed thin, lacks transparency, can completely conceal the color of the magnetic particles present at the bottom of the cell space at the time of erasure of the screen, and results in little breaks in lines at the boundary portions at the time of display of an image.
To achieve the first object, according to a third aspect of the present invention, there is provided a magnetophoresis type display device comprising:
a transparent front panel sheet,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space of a thickness of 0.8 to 1.5 mm into a large number of cells, and
a liquid dispersion containing magnetic particles to be sealed inside the cells formed by partitioning by the partitioning member,
the magnetic particles containing 60 to 90 wt % of a magnetic material and 10 to 40 wt % of a synthetic resin and/or coloring agent, the mean particle size of the magnetic particles being 50 to 200 xcexcm, the magnetization of the magnetic particles when a 200 Oe magnetic field is applied to the magnetic particles being at least 8.0 emu/g, and the magnetization of the magnetic particles when a 500 Oe magnetic field is applied to the magnetic particles being at least 20.0 emu/g,
the liquid dispersion containing 80 to 90 wt % of a single-color fluid and 10 to 20 wt % of magnetic particles.
Further, the present inventors engaged in intensive studies to achieve the second object and as result discovered that by maintaining the thickness of the sealed space between the front panel sheet and the back panel sheet, the various conditions of the colored magnetic particles, the various conditions of the liquid dispersion, etc. in an overall predetermined relationship, it was first possible to eliminate image breaks in display at the boundary portions of the individual cells, eliminate color bleeding, and improve the clearness of the hues and the resolution of a color display image and thereby completed a fourth aspect of the invention.
That is, according to the fourth aspect of the present invention, there is provided a magnetophoresis type color display device comprising:
a transparent front panel sheet,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space of a thickness of 0.8 to 1.5 mm into a large number of cells,
a first liquid dispersion containing first colored magnetic particles to be sealed inside selected specific cells formed by partitioning by the partitioning member, and
a second liquid dispersion containing second colored magnetic particles to be sealed inside selected specific cells in the cells in which the first liquid dispersion is not sealed and colored different from the first colored magnetic particles,
the mean particle sizes of the first colored magnetic particles and the second colored magnetic particles being 50 to 200 xcexcm and the magnetization of the magnetic particles when a 500 Oe magnetic field is applied to the magnetic particles being at least 20.0 emu/g.
The first liquid dispersion is preferably a liquid comprised of a single-color fluid in which the first colored magnetic particles are dispersed, while the second liquid dispersion is preferably a single-color fluid in which the second colored magnetic particles are dispersed. Note that in addition to the first liquid dispersion and the second liquid dispersion, it is also possible to provide a third liquid dispersion containing third colored magnetic particles colored different from the first colored magnetic particles and the second colored magnetic particles. In this case, the colors of the first to third colored magnetic particles are mutually different and preferably ones of the three primary colors (red, green, and blue). Further, the magnetophoresis type color display device according to this aspect of the present invention may also have liquid dispersions containing magnetic particles colored different than the first to third colored magnetic particles.
In the case of a magnetophoresis type color display device, the recording magnetic member preferably has a magnetic force of an extent giving an effective magnetic flux density of 100 to 500 Gauss at the outer surface of the back panel sheet in the state when the recording magnetic member is brought into contact with the outer surface of the front panel sheet. Further, in the case of a magnetophoresis type color display device, the erasing magnetic member preferably has a magnetic force of an extent giving an effective magnetic flux density of 300 to 1500 Gauss at the outer surface of the front panel sheet in the state when the erasing magnetic member is brought into contact with the outer surface of the back panel sheet.
When the magnetic force of the recording magnetic member is too small, the magnetophoresis action in the cells is weak, so the display of color at the screen is difficult. Further, when the magnetic force of the recording magnetic member is too large, the magnetic field is too strong, so when the magnetically floating colored magnetic particles are displayed at the screen, the resolution of the color displayed object tends to be deteriorated.
Further, if the magnetic force of the erasing magnetic member is too small, the magnetophoresis action in the cells is weak, it becomes difficult to pull back the colored magnetic particles from the panel screen side, and the erasure of the displayed object at the screen tends to become difficult. Further, if the magnetic force of the erasing magnetic member is too large, the magnetic field is too strong, so the colored magnetic particles magnetically floating for erasure remain at the inner surface of the panel screen as xe2x80x9cstubblexe2x80x9d and therefore the display of the panel screen cannot be cleanly erased.
In the magnetophoresis type color display device according to the fourth aspect of the present invention, by establishing specific regions of limits for the thickness of the sealed space, the particle size of the colored magnetic particles, the magnetization characteristics, the viscosity and composition of the single-color fluid (white fluid), and/or the effective magnetic flux density of the recording magnetic member and the erasing magnetic member, it is possible to obtain a magnetophoresis type color display device which can give a clear color display at the panel screen and further can be cleanly erased.
The present inventors engaged in intensive studies to achieve the third object and as a result discovered that by specifying the material of the front panel sheet and the thickness of the sealed space between the front panel sheet and the back panel sheet, it is possible to obtain a device which is environmentally friendly when disposed of and further eliminates image breaks in display at the boundary portions of the individual cells and can improve the contrast and thereby completed a fifth aspect of the invention.
That is, according to the fifth aspect of the present invention, there is provided a magnetophoresis type display device comprising
a transparent front panel sheet comprised of polyethylene terephthalate,
a back panel sheet arranged with respect to the front panel sheet so as to form a sealed space with it,
a partitioning member provided between the front panel sheet and the back panel sheet for partitioning the sealed space of a thickness of 0.8 to 1.5 mm into a large number of cells, and
a liquid dispersion containing magnetic particles to be sealed inside the individual cells formed by partitioning by the partitioning member.
In the magnetophoresis type display device according to the fifth aspect, the recording magnetic member is not particularly limited, but preferably has a magnetic force of an extent giving an effective magnetic flux density of 100 to 500 Gauss at the outer surface of the back panel sheet in the state when the recording magnetic member is brought into contact with the outer surface of the front panel sheet. Further, the erasing magnetic member preferably has a magnetic force of an extent giving an effective magnetic flux density of 100 to 1500 Gauss at the outer surface of the front panel sheet in the state when the erasing magnetic member is brought into contact with the outer surface of the back panel sheet.
In the magnetophoresis type display device according to the fifth aspect of the present invention, the front panel sheet is comprised of polyethylene terephthalate (PET), so is easier to dispose of compared with a front panel sheet comprised of polyvinyl chloride and is environmentally friendly. Further, the present inventors discovered that the contrast at the panel screen is improved by making the material of the front panel sheet PET.
To achieve the third object, according to the present invention, there is provided a first process of production of a magnetophoresis type display device comprising the steps of:
attaching to a depression of a transparent front panel sheet formed with a depression at its inner surface and comprised of polyethylene terephthalate a partitioning member formed with a large number of cell spaces,
filling the insides of the cell spaces of the partitioning member with a liquid dispersion containing magnetic particles, and
bonding an inner surface of an outer periphery of a back panel sheet and an inner surface of an outer periphery of the front panel sheet together so as to seal the liquid dispersion filled at the insides of the cell spaces.
The process is preferably one in which the partitioning member is comprised of a honeycomb structure and is supplied with the honeycomb structure in a compact state and further comprises the steps of:
opening up the compact honeycomb structure so as to open up the cell spaces,
coating a solidifying agent on the honeycomb structure in the state with the cell spaces opened up, and
attaching the honeycomb structure coated with the solidifying agent to the depression of the front panel sheet.
According to the first process of production of the present invention, it is possible to extremely easily produce a magnetophoresis type display device which is easy to dispose of, is environmentally friendly, and can be improved in the contrast at the screen.
Further, the present inventors engaged in intensive studies to achieve the fourth object and as a result discovered that by filling the inside of the cell spaces of a partitioning member attached to a depression of a transparent front panel with a liquid dispersion containing magnetic particles and then squeegeeing the liquid dispersion protruding from the cell spaces of the partitioning member, it is possible to obtain a magnetophoresis type display device which eliminates image breaks in display at the boundary portions of the individual cells and can improve the contrast and thereby completed the next aspect of the present invention.
That is, according to the present invention, there is provided a second process of production of a magnetophoresis type display device comprising the steps of:
attaching to a depression of a transparent front panel sheet formed with a depression at its inner surface a partitioning member formed with a large number of cell spaces,
filling the insides of the cell spaces of the partitioning member with a liquid dispersion containing magnetic particles,
squeegeeing the liquid dispersion protruding from cell spaces of the partitioning member, and
bonding an inner surface of an outer periphery of a back panel sheet and an inner surface of an outer periphery of the front panel sheet together so as to seal the liquid dispersion filled at the insides of the cell spaces.
The second process of production of the present invention preferably further comprises the steps of:
preparing as the liquid dispersion at least a first liquid dispersion containing first colored magnetic particles and a second liquid dispersion containing second colored magnetic particles colored different from the first colored magnetic particles,
masking by a first masking member the cells other than selected specific cells in the cells formed by partitioning by the partitioning member and filling only the insides of the selected specific cells with the first liquid dispersion,
squeegeeing the liquid dispersion from the top of the first masking member,
removing the first masking member, masking by a second masking member cells other than selected specific cells in the cells not filled with the first liquid dispersion and filling only the insides of the selected specific cells not masked by the second masking member with the second liquid dispersion, and
squeegeeing the liquid dispersion from the top of the second masking member.
Further, the second process of production of the present invention is preferably one in which the partitioning member is comprised of a honeycomb structure and is supplied with the honeycomb structure in a compact state and further comprises the steps of:
opening up the compact honeycomb structure so as to open up the cell spaces,
coating a solidifying agent on the honeycomb structure in the state with the cell spaces opened up, and
attaching the honeycomb structure coated with the solidifying agent to the depression of the front panel sheet.
The masking member is not particularly limited and may be a masking tape, masking sheet, printing screen, metal mask, etc. The material of the masking member is not particular limited and may for example be a metal, synthetic resin, fiber, etc.
Further, the squeeging tool used for the squeegeeing operation is not particularly limited and may be an elastic wiping blade comprised of rubber or a synthetic resin, a metal squeegeeing blade, etc.
Further, the squeegeeing speed of the wiping tool is not particularly limited, but preferably is 10 to 300 mm/sec, more preferably 30 to 100 mm/sec. At such a squeegeeing speed, it is possible to obtain an excellent squeegeeing effect.
Further, at the pressing force of the squeegeeing tool on the partitioning member at the time of squeegeeing is not particularly limited, but preferably is 10 to 200 g/mm2, more preferably 50 to 150 g/mm2. If the pressing force is too small, the squeegeeing effect is lost, while if the pressing force is too large, the partitioning member tends to be damaged.
In the second process of production according to the present invention, by filling the insides of the cell spaces of a partitioning member attached to a depression of a transparent front panel with a liquid dispersion containing magnetic particles and then wiping away the liquid dispersion protruding from the cell spaces of the partitioning member, it is possible to eliminate the excess or shortage of liquid dispersion in the individual cells and as a result eliminate breaks in display at the boundary portions of the individual cells and improve the contrast.
Further, in this aspect of the present invention, by masking by a masking member the cells other than selected specific cells in the cells formed by partitioning by the partitioning member attached to a depression of a transparent front panel, filling only the insides of the selected specific cells with a liquid dispersion containing specific colored magnetic particles, then wiping the top of the masking member and repeating this operation for each of the colored magnetic particles, it is possible to eliminate excess or shortage of liquid dispersion in the individual cells and as a result eliminate image breaks in display at the boundary portions of the individual cells, eliminate color bleeding, and improve the clearness of the hues and the resolution of the color display image.
The applications of the magnetophoresis type display device (including magnetophoresis type color display device) according to the present invention are not particularly limited. The device may be broadly used for toys for children, teaching materials, practice writing boards, game boards, record boards, memo boards, blackboards, whiteboards, advertising boards, portable memo pads, etc. The locations of installation of the magnetophoresis type display device according to the present invention are also not particularly limited. They are not limited to the insides of factories, schools, and other buildings and may also be outdoors at train platforms, ticketing gates, construction sites, etc. or in the water etc.